This study examined the efficacy of the Theory of Planned Behavior (TpB) among Korean college students on intentions of condom use. A cross-sectional, correlational design was conducted with an exploratory survey method. Young men and women aged 18–25 were recruited from a university in Seoul, Korea using a flyer and self-referral. Students completed a background and sexual behavior questionnaire, a parent–adolescent communication scale, and instruments derived from the TpB. Age, parent–adolescent communication, and perceived risk of sexual behavior were added to the model as potential determinants of intention of condom use. All the TpB components significantly predicted intention of condom use for young men, but only condom attitude and condom efficacy significantly predicted intention of condom use for young women. Age and quality of parent–adolescent communication indirectly affected the intention of condom use; however, perceived risk of sexual behavior did not predict intention of condom use, nor was it affected by age. Older students had a higher condom efficacy and a higher perceived peer norm of condom use. The quality of parent–adolescent communication significantly predicted a higher condom efficacy for young men, but not women.